JP2886037B2 - Hydrophobic fine silica and method for producing the same - Google Patents

Hydrophobic fine silica and method for producing the same

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Publication number
JP2886037B2
JP2886037B2 JP15238293A JP15238293A JP2886037B2 JP 2886037 B2 JP2886037 B2 JP 2886037B2 JP 15238293 A JP15238293 A JP 15238293A JP 15238293 A JP15238293 A JP 15238293A JP 2886037 B2 JP2886037 B2 JP 2886037B2
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JP
Japan
Prior art keywords
fine silica
groups
hydrophobic
hexamethyldisilazane
silica
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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JP15238293A
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Japanese (ja)
Other versions
JPH0710524A (en
Inventor
正博 中村
一寿 延本
尊凡 永野
芳雄 美谷
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Tokuyama Corp
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Tokuyama Corp
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Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【産業上の利用分野】本発明は、表面に十分な量の疎水
基を有し、しかもOH基の量は少なく、高い疎水性を示
す微細シリカおよびその製造方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to fine silica which has a sufficient amount of hydrophobic groups on its surface, has a small amount of OH groups and exhibits high hydrophobicity, and a method for producing the same.

【0002】[0002]

【従来の技術】クロロシランの火炎熱分解によって製造
されるシリカは、比表面積が50〜500m2/g程度
の微細シリカであり、一般にはフュームドシリカと呼ば
れている。この微細シリカは樹脂の充填・補強材や粉末
の流動化剤として用いられているが、これらの用途に使
用するためには微細シリカの表面を疎水性にすることが
しばしば必要とされている。疎水化処理された微細シリ
カを上記の用途に用いた場合の効果は一概にはいえない
が、例えば、シリコーン樹脂の充填・補強材として使用
した場合には微細シリカ粒子の分散性を高めてシリコー
ン樹脂の伸びや機械的強度を向上させる効果があり、粉
末の流動化剤として用いた場合にはその流動性を著しく
向上させる効果がある。
2. Description of the Related Art Silica produced by flame pyrolysis of chlorosilane is fine silica having a specific surface area of about 50 to 500 m 2 / g, and is generally called fumed silica. This fine silica is used as a filler or reinforcing material for resin or as a fluidizing agent for powder, but it is often necessary to make the surface of fine silica hydrophobic for use in these applications. The effect of using hydrophobized fine silica for the above applications is not certain, but for example, when used as a filler / reinforcing material for silicone resin, the dispersion of fine silica particles is It has the effect of improving resin elongation and mechanical strength, and has the effect of significantly improving its flowability when used as a powder fluidizer.

【0003】このような効果を求め、微細シリカの表面
を高度に疎水化する試みが従来から広く行われており、
メチルクロロシランやシランカップリング剤などが疎水
化処理剤として用いられてきた。このような疎水化処理
剤のなかでも、適度に大きい分子量の化合物が高疎水性
微細シリカを得るためには有効であった。例えば、微細
シリカを分子量の大きい疎水化処理剤であるシリコーン
オイルで処理すると、後述する方法で測定された修飾疎
水度で表される疎水性の程度が70%の微細シリカを得
ることができる。しかし、この場合のシリコーンオイル
の大部分は、単に微細シリカの表面に付着しているだけ
で、表面と反応しているわけではない。したがって、充
填する樹脂の種類によっては、修飾されたシリコーンオ
イルが表面から離れて樹脂中に溶け出し、分散した微細
シリカ粒子の疎水度が期待に反して悪化することが起こ
り得る。
[0003] In order to obtain such an effect, attempts to make the surface of fine silica highly hydrophobic have been widely performed.
Methylchlorosilane and silane coupling agents have been used as hydrophobizing agents. Among such hydrophobizing agents, compounds having a moderately high molecular weight were effective for obtaining highly hydrophobic fine silica. For example, when the fine silica is treated with a silicone oil which is a hydrophobizing agent having a high molecular weight, it is possible to obtain a fine silica having a degree of hydrophobicity represented by a modified hydrophobicity of 70% as measured by a method described later. However, most of the silicone oil in this case simply adheres to the surface of the fine silica and does not react with the surface. Therefore, depending on the type of the resin to be filled, the modified silicone oil may be separated from the surface and melt into the resin, and the hydrophobicity of the dispersed fine silica particles may be deteriorated unexpectedly.

【0004】また、別の高疎水化処理の方法としては、
微細シリカをヘキサメチルジシラザンで処理する方法が
ある(特開昭62−171913号公報)。この方法
は、ヘキサメチルジシラザンが微細シリカの表面のOH
基と反応することを利用したものである。従って、この
方法により疎水化処理された微細シリカの表面にはトリ
メチルシリル基が化学結合により固定されており、修飾
疎水度60%以上の微細シリカを得ることができる。こ
の方法において、微細シリカの表面に十分な量のトリメ
チルシリル基を導入するためには微細シリカを予め水で
濡らせて表面のOH基の数を増加させることが必要であ
った。この方法で得た微細シリカは、その修飾疎水度が
前述のシリコーンオイル処理で得た微細シリカの修飾疎
水度と比べて劣るが、疎水基が表面に化学的に結合して
いることに特徴がある。
[0004] Further, as another method of high hydrophobicity treatment,
There is a method of treating fine silica with hexamethyldisilazane (JP-A-62-171913). In this method, hexamethyldisilazane is used to remove OH on the surface of fine silica.
It utilizes the fact that it reacts with a group. Therefore, trimethylsilyl groups are fixed on the surface of the fine silica hydrophobized by this method through chemical bonding, and fine silica having a modified hydrophobicity of 60% or more can be obtained. In this method, in order to introduce a sufficient amount of trimethylsilyl groups to the surface of the fine silica, it was necessary to wet the fine silica in advance with water to increase the number of OH groups on the surface. The modified silica obtained by this method is inferior to the modified hydrophobicity of the fine silica obtained by the above-described silicone oil treatment, but is characterized by a hydrophobic group chemically bonded to the surface. is there.

【0005】[0005]

【発明が解決しようとする課題】しかしながら、上記の
方法で得た微細シリカは修飾疎水度で表した疎水性の程
度が良好であるが、その応用分野においては、さらに高
疎水性の微細シリカの出現が望まれてきた。そのような
高疎水性微細シリカが出現すれば、例えば、樹脂の充填
剤として用いた場合、樹脂と微細シリカの濡れ性向上や
分散性向上に伴う種々の応用特性の改善が期待できる。
より具体的には、エポキシや不飽和ポリエステル樹脂に
充填剤として混合して、樹脂の粘度やチキソトロピー性
の経時的な安定性の向上が期待される。また、このよう
な微細シリカをシリコーンのような各種シーラントに混
合して使用すると、カートリッジからの押し出し性の経
時的な安定性向上効果が期待される。
However, the fine silica obtained by the above method has a good degree of hydrophobicity represented by the modified hydrophobicity. Appearance has been desired. When such highly hydrophobic fine silica appears, for example, when it is used as a filler for a resin, various application characteristics can be expected to be improved due to improvement in wettability and dispersibility of the resin and the fine silica.
More specifically, it is expected to improve the viscosity and thixotropic properties of the resin over time by mixing it with a filler in an epoxy or unsaturated polyester resin. When such fine silica is mixed with various sealants such as silicone and used, an effect of improving the stability over time of the extrudability from the cartridge is expected.

【0006】ところで、前記した疎水化処理方法により
得られた微細シリカは、修飾疎水度が60%以上の高疎
水性を示すが、別の観点から見るとその疎水性の程度は
必ずしも良好でないことが判明した。すなわち、上記の
微細シリカは修飾疎水度は良好であるが、その表面にO
H基を多数有していることがわかった。例えば、シリコ
ーンオイルで処理した微細シリカは、シリコーンオイル
が表面OH基と反応せずに単に付着されているだけであ
り、1個/nm2程度の表面OH基が残存している。ま
た、ヘキサメチルジシラザンで微細シリカを処理する方
法は、ヘキサメチルジシラザンが微細シリカの表面のO
H基と反応することを利用したものであるために、微細
シリカの表面に予めOH基を導入しなければならず、そ
うすると、導入されたOH基の一部がヘキサメチルジシ
ラザンと反応せずに微細シリカ表面に残存する。
By the way, the fine silica obtained by the above-mentioned hydrophobizing treatment shows high hydrophobicity with a modified hydrophobicity of 60% or more, but from another point of view, the degree of hydrophobicity is not necessarily good. There was found. That is, the above fine silica has a good modified hydrophobicity, but has
It was found to have many H groups. For example, fine silica treated with silicone oil has a surface OH group of about 1 / nm 2 remaining only because the silicone oil does not react with the surface OH group and is merely attached. Further, the method of treating fine silica with hexamethyldisilazane is such that hexamethyldisilazane is treated with O on the surface of the fine silica.
In order to utilize the reaction with the H group, an OH group must be introduced in advance to the surface of the fine silica, and a part of the introduced OH group does not react with hexamethyldisilazane. At the surface of the fine silica.

【0007】従来の疎水化方法では、表面を高性能な疎
水基で修飾することにのみ目が向けられた。しかし、そ
れが表面OH基の数を減少させることには必ずしもつな
がらなかったと思われる。前述のシリコーンオイルやヘ
キサメチルジシラザンによる疎水化処理は、モノメチル
クロロシランやジメチルジクロロシランよりも高性能の
疎水基を表面に導入することによって表面の疎水性を増
すことができるが、表面のOH基の減少にはつながら
ず、総合的な疎水度が必ずしも良好ではない。
[0007] In the conventional hydrophobizing method, attention was focused only on modifying the surface with a high-performance hydrophobic group. However, it seems that it did not always reduce the number of surface OH groups. The above-mentioned hydrophobic treatment with silicone oil or hexamethyldisilazane can increase the hydrophobicity of the surface by introducing a hydrophobic group having a higher performance than monomethylchlorosilane or dimethyldichlorosilane to the surface. And the overall hydrophobicity is not always good.

【0008】このように、従来の方法で疎水化された微
細シリカは修飾疎水度は良好であるが、その表面にOH
基を多数有しており、微細シリカの総合的な疎水性の程
度を判断するには、表面を修飾した疎水基に基づく疎水
度と表面OH基が少ないことに基づく疎水度の両方で論
じなければならないことが判明した。
As described above, fine silica hydrophobized by the conventional method has a good modified hydrophobicity, but OH
In order to judge the overall degree of hydrophobicity of fine silica, which has many groups, it is necessary to discuss both the degree of hydrophobicity based on the surface-modified hydrophobic group and the degree of hydrophobicity based on the small number of surface OH groups. It turned out to be necessary.

【0009】そこで本発明者らは、このように総合的な
疎水度が良好な微細シリカを得ることを目的として、表
面に疎水基が十分な量存在し、修飾疎水度が良好で、し
かもOH基の数の少ない微細シリカを得るために研究を
重ねてきた。
In order to obtain fine silica having good overall hydrophobicity, the inventors of the present invention have found that a sufficient amount of hydrophobic groups are present on the surface, the modified hydrophobicity is good, and Studies have been made to obtain fine silica having a small number of groups.

【0010】[0010]

【課題を解決するための手段】その結果、疎水化前の微
細シリカとして表面OH基の比較的少ないものを使用
し、ヘキサメチルジシラザンを接触させる際に水蒸気を
存在させることによって上記目的を達成することができ
ることを見いだし、本発明を完成するに至った。
As a result, the above object is achieved by using fine silica having relatively few surface OH groups as fine silica before hydrophobization and allowing water vapor to be present when contacting hexamethyldisilazane. The inventors have found that the present invention can be performed, and have completed the present invention.

【0011】即ち、本発明は、単位表面積当たりの表面
のOH基の数が0.3個/nm2以下であり、且つ修飾
疎水度が60%以上であることを特徴とする疎水性微細
シリカである。
That is, the present invention provides a hydrophobic fine silica characterized in that the number of OH groups on the surface per unit surface area is not more than 0.3 / nm 2 and the modified hydrophobicity is not less than 60%. It is.

【0012】本発明の疎水性微細シリカは、比表面積が
50〜500m2/g、特に150〜300m2/gの微
細粒子よりなるシリカである。このような微細シリカ
は、通常、ハロゲノシランの火炎熱分解あるいは加水分
解で製造することができる。
The hydrophobic fine silica of the present invention is a silica composed of fine particles having a specific surface area of 50 to 500 m 2 / g, particularly 150 to 300 m 2 / g. Such fine silica can usually be produced by flame pyrolysis or hydrolysis of halogenosilane.

【0013】本発明の疎水性微細シリカは、単位表面積
当たりの表面のOH基の数が0.3個/nm2以下であ
り、且つ修飾疎水度が60%以上でなければならない。
本発明の疎水性微細シリカは、このように表面OH基数
が少なく、且つ修飾疎水度が高いことの両者の総合的な
効果により、著しく疎水性の高い微細シリカとなってい
る。
The number of OH groups on the surface per unit surface area of the hydrophobic fine silica of the present invention must be 0.3 / nm 2 or less, and the modified hydrophobicity must be 60% or more.
The hydrophobic fine silica of the present invention is a fine silica having extremely high hydrophobicity due to the combined effects of the small number of surface OH groups and the high modified hydrophobicity.

【0014】表面OH基の数および修飾疎水度のいずれ
か一方が上記した範囲を外れた場合には、本発明の疎水
性微細シリカと比べ、十分な疎水性を有する微細シリカ
とはならない。例えば、表面OH基の数が上記値を越え
たときは、一般に湿度環境下で大きな吸湿量を示す傾向
にある。また、修飾疎水度が上記値未満のときは、例え
ば、シリコーンに分散させると微細シリカの分散が十分
でないために粘度が高くなり、また、その粘度の経時変
化が大きくなるという傾向を示す。これらの二つの傾向
は、必ずしも明確に区別できるものでなく、少なからず
相互に影響を及ぼし合うものと考えられる。
If any one of the number of surface OH groups and the modified hydrophobicity is out of the above range, the fine silica having sufficient hydrophobicity will not be obtained as compared with the hydrophobic fine silica of the present invention. For example, when the number of surface OH groups exceeds the above value, it generally tends to show a large amount of moisture absorption in a humid environment. Further, when the modified hydrophobicity is less than the above value, for example, when dispersed in silicone, the dispersion of fine silica is not sufficient, so that the viscosity tends to increase, and the viscosity tends to change with time. These two tendencies are not always clearly distinguishable, and are thought to have some influence on each other.

【0015】表面のOH基の数は0.3個/nm2以下
であればよいが、0.25個/nm2以下、さらに0.
20個/nm2以下であることが高疎水性の微細シリカ
とするために好ましい。なお、本発明における単位表面
積当たりの表面のOH基の数は、後述するカールフィッ
シャー法により測定した表面水分量を基に計算した値で
ある。また、修飾疎水度は60%以上であればよいが、
さらに62%以上であることが好ましい。修飾疎水度は
後述する方法により測定することができる。
The number of OH groups on the surface may be not more than 0.3 / nm 2, but is not more than 0.25 / nm 2 .
It is preferable that the number is 20 particles / nm 2 or less in order to obtain highly hydrophobic fine silica. In the present invention, the number of OH groups on the surface per unit surface area is a value calculated based on the surface moisture content measured by the Karl Fischer method described later. Further, the modified hydrophobicity may be 60% or more,
Further, it is preferably at least 62%. The modified hydrophobicity can be measured by the method described below.

【0016】本発明の疎水性微細シリカは粗粒の少ない
ものであることが好ましく、通常は目開き45μmの篩
残が0.1重量%以下であることが好ましい。また、本
発明の疎水性微細シリカは修飾疎水度に寄与する疎水基
をその表面に有するために疎水基の量に応じた炭素を表
面に有しており、その炭素量は後述する方法によって測
定することができる。例えば、本発明の疎水性微細シリ
カの炭素量は通常2.7〜5.0重量%の範囲である。
さらに、本発明の疎水性微細シリカは後述する方法によ
り製造された場合には反応副生物であるアンモニアを吸
着しているが、これが特定の用途において問題となると
きは窒素ガスを吹き込むことにより副生物や未反応物を
パージすることができ、アンモニア量を100ppm以
下とすることができる。また、本発明の疎水生微細シリ
カを中性近辺、例えば、後述する方法で測定されたpH
を5.0〜8.0の範囲とすることができる。
The hydrophobic fine silica of the present invention preferably has a small amount of coarse particles, and usually has a sieve residue having a mesh size of 45 μm of 0.1% by weight or less. Further, the hydrophobic fine silica of the present invention has carbon on its surface according to the amount of the hydrophobic group in order to have a hydrophobic group contributing to the modified hydrophobicity on its surface, and the carbon amount is measured by the method described below. can do. For example, the carbon content of the hydrophobic fine silica of the present invention is usually in the range of 2.7 to 5.0% by weight.
Furthermore, when the hydrophobic fine silica of the present invention is produced by the method described below, it adsorbs ammonia which is a reaction by-product. Biological substances and unreacted substances can be purged, and the amount of ammonia can be reduced to 100 ppm or less. In addition, the hydrophobic raw fine silica of the present invention is near neutral, for example, pH measured by the method described below.
Can be in the range of 5.0 to 8.0.

【0017】本発明の疎水性微細シリカは、どのような
方法によって得てもよいが、次に述べる方法によって好
適に製造することができる。単位表面積当たりの表面の
OH基の数が1.5個/nm2以下である微細シリカを
水蒸気の存在下にヘキサメチルジシラザンと接触させる
方法である。
Although the hydrophobic fine silica of the present invention may be obtained by any method, it can be suitably produced by the following method. This is a method in which fine silica having the number of OH groups on the surface per unit surface area of 1.5 / nm 2 or less is contacted with hexamethyldisilazane in the presence of water vapor.

【0018】単位表面積当たりの表面のOH基の数が
1.5個/nm2以下である微細シリカを得る方法は種
々あるが、例えば、ハロゲノシランの火炎熱分解あるい
は加水分解で製造された微細シリカの反応直後の吸湿し
ていない状態のものを使用するか、または、吸湿を避け
て保存したものを使用すれば良い。また、微細シリカを
モノメチルクロロシランやトリメチルクロロシランで表
面処理をすることによっても調製することができる。こ
の微細シリカの単位表面積当たりの表面のOH基の数が
1.5個/nm2を越えると、ヘキサメチルジシラザン
と接触させた後においても未反応の表面OH基の数が多
く残存し、微細シリカの表面が親水性となるために好ま
しくない。ヘキサメチルジシラザンと接触させる前の微
細シリカの表面のOH基の数は1.5個/nm2以下で
あればよいが、得られる疎水性微細シリカの表面OH基
の数をできるだけ減少させるため、0.5個/nm2
下であることが好ましい。
There are various methods for obtaining fine silica in which the number of OH groups on the surface per unit surface area is 1.5 / nm 2 or less. For example, fine silica prepared by flame pyrolysis or hydrolysis of halogenosilane is used. It is preferable to use a silica that has not absorbed moisture immediately after the reaction of silica, or a silica that has been stored while avoiding moisture absorption. Further, it can also be prepared by subjecting fine silica to a surface treatment with monomethylchlorosilane or trimethylchlorosilane. When the number of OH groups on the surface per unit surface area of the fine silica exceeds 1.5 / nm 2 , a large number of unreacted surface OH groups remain even after contact with hexamethyldisilazane, It is not preferable because the surface of the fine silica becomes hydrophilic. The number of OH groups on the surface of the fine silica before contacting with hexamethyldisilazane may be 1.5 / nm 2 or less, but in order to reduce the number of OH groups on the surface of the resulting hydrophobic fine silica as much as possible. , 0.5 / nm 2 or less.

【0019】ヘキサメチルジシラザンと接触させる前の
微細シリカは、通常、比表面積が50〜500m2
g、特に好ましくは、200〜400m2/gであり、
表面処理後は、通常150〜300m2/gの範囲とな
る。
The fine silica before being brought into contact with hexamethyldisilazane usually has a specific surface area of 50 to 500 m 2 /
g, particularly preferably from 200 to 400 m 2 / g,
After the surface treatment, it is usually in the range of 150 to 300 m 2 / g.

【0020】本発明においては、この微細シリカを水蒸
気の存在下にヘキサメチルジシラザンと接触させる。ヘ
キサメチルジシラザンは、液体、気体の別なく使用可能
である。ヘキサメチルジシラザンの使用量は特に限定さ
れないが、通常、微細シリカ1kg当り0.2〜10.
0kgの範囲から選べばよい。
In the present invention, the fine silica is brought into contact with hexamethyldisilazane in the presence of steam. Hexamethyldisilazane can be used regardless of whether it is a liquid or a gas. The amount of hexamethyldisilazane to be used is not particularly limited, but is usually 0.2 to 10.3 kg / kg of fine silica.
It can be selected from a range of 0 kg.

【0021】本発明においては、上記のヘキサメチルジ
シラザンと微細シリカとの接触を水蒸気の存在下に行う
ことが重要である。従来、トリメチルシリル基は、ヘキ
サメチルジシラザンが微細シリカ表面のOH基と反応す
ることにより微細シリカ表面に導入されるために、元の
微細シリカには十分な量のOH基が必要であると考えら
れていた。しかしながら、前述のように、OH基の一部
はヘキサメチルジシラザンとの接触によっても未反応の
状態で残存し、そのために疎水基で修飾後も微細シリカ
表面のOH基が残存し、好ましくないことが判明した。
これを防ぐためには、元の微細シリカは表面のOH基が
比較的少ないほうがよい。しかし、表面OH基の量が少
ないとヘキサメチルジシラザンの反応性が悪く、十分な
量のトリメチルシリル基を導入することができないとい
う矛盾が生じていた。
In the present invention, it is important that the above-mentioned contact between hexamethyldisilazane and fine silica is carried out in the presence of water vapor. Conventionally, trimethylsilyl groups are considered to require a sufficient amount of OH groups in the original fine silica because hexamethyldisilazane is introduced into the fine silica surface by reacting with the OH groups on the fine silica surface. Had been. However, as described above, some of the OH groups remain in an unreacted state even by contact with hexamethyldisilazane, so that the OH groups on the fine silica surface remain even after modification with a hydrophobic group, which is not preferable. It has been found.
To prevent this, the original fine silica preferably has relatively few OH groups on the surface. However, when the amount of surface OH groups is small, the reactivity of hexamethyldisilazane is poor, and contradiction arises that a sufficient amount of trimethylsilyl groups cannot be introduced.

【0022】ところが、本発明のように、ヘキサメチル
ジシラザンとの接触を水蒸気の存在下に行うことによっ
て、表面のOH基の量が少ない微細シリカを使用するに
もかかわらず、得られる疎水性微細シリカの表面に、以
外にも十分な量のトリメチルシリル基を導入することが
でき、しかも、表面OH基の数を極めて少なくすること
ができた。この理由は定かではないが、水蒸気が触媒と
して作用し、ヘキサメチルジシラザンの反応性を向上さ
せたものと思われる。
However, by contacting with hexamethyldisilazane in the presence of water vapor as in the present invention, the hydrophobicity obtained is small despite the use of fine silica having a small amount of OH groups on the surface. In addition to the surface of the fine silica, a sufficient amount of other trimethylsilyl groups could be introduced, and the number of surface OH groups could be extremely reduced. Although the reason for this is not clear, it is considered that the steam acts as a catalyst to improve the reactivity of hexamethyldisilazane.

【0023】本発明における水蒸気の使用量は特に制限
されないが、一般にはヘキサメチルジシラザンと水蒸気
との供給比率が、水蒸気/ヘキサメチルジシラザン=1
/4〜2/1(モル比)となるように選択することが好
ましい。水蒸気は微細シリカをヘキサメチルジシラザン
と接触させる反応器中に間欠的に供給してもよく、ま
た、連続的に供給しても良い。通常は、反応器中にヘキ
サメチルジシラザンと水蒸気とを一定の比率で連続的ま
たは間欠的に供給することが好ましい。
The amount of steam used in the present invention is not particularly limited, but generally, the supply ratio of hexamethyldisilazane to steam is such that steam / hexamethyldisilazane = 1.
It is preferable to select so as to be / 4 to 2/1 (molar ratio). Water vapor may be supplied intermittently or continuously in a reactor in which fine silica is brought into contact with hexamethyldisilazane. Usually, it is preferable to supply hexamethyldisilazane and steam at a constant ratio to the reactor continuously or intermittently.

【0024】微細シリカとヘキサメチルジシラザンの接
触時の温度は特に制限ないが、上記したようにヘキサメ
チルジシラザンを気体状態で接触させることが好ましい
ため、ヘキサメチルジシラザンの沸点以上の温度、一般
には150〜250℃の温度を採用することが好まし
い。また、接触時間は特に制限ないが、通常0.5〜2
時間の範囲から採用すればよい。
The temperature at the time of contact between the fine silica and hexamethyldisilazane is not particularly limited. However, since it is preferable that hexamethyldisilazane be contacted in a gaseous state as described above, a temperature higher than the boiling point of hexamethyldisilazane, Generally, it is preferable to employ a temperature of 150 to 250 ° C. The contact time is not particularly limited, but is usually 0.5 to 2 times.
It may be adopted from the time range.

【0025】なお、反応の形式は特に制限されず、例え
ば、バッチ式、連続式のいずれでもよく、また、反応装
置も流動床式、固定床式あるいは単なる混合器であって
もよい。反応後は未反応物や副生物を窒素でパージして
乾燥することが、得られる疎水性微細シリカのNH3
量を低減させることができるために好ましい。
The type of the reaction is not particularly limited, and may be, for example, a batch type or a continuous type, and the reaction apparatus may be a fluidized bed type, a fixed bed type, or a simple mixer. After the reaction, unreacted substances and by-products are preferably purged with nitrogen and dried because the NH 3 content of the obtained hydrophobic fine silica can be reduced.

【0026】本発明においては、水蒸気の存在下におけ
る微細シリカとヘキサメチルジシラザンとの接触を行う
前に、まず、微細シリカをメチルトリクロルシラン、ジ
メチルジクロルシラン等のアルキルハロゲノシランと接
触させておくことにより、さらに優れた疎水性微細シリ
カを製造することができる。
In the present invention, before the fine silica is brought into contact with hexamethyldisilazane in the presence of water vapor, the fine silica is first brought into contact with an alkylhalogenosilane such as methyltrichlorosilane or dimethyldichlorosilane. By doing so, more excellent hydrophobic fine silica can be produced.

【0027】この方法は、シリカ表面のOH基にアルキ
ルハロゲノシランを反応させて予め比較的立体障害の小
さいアルキルハロゲノシリル基を導入し、残存するOH
基を反応性の高いヘキサメチルジシラザンと反応させる
方法である。アルキルハロゲノシリル基の導入のみで
は、本発明の特定の表面OH数と修飾疎水度とを共に満
足するものは得れないが、さらに反応性の高いヘキサメ
チルジシラザンを水蒸気の存在下で反応させることによ
り、著しく疎水度の優れた微細シリカを得ることができ
る。この方法は、修飾疎水度を高め、かつ、表面OH基
の数を最も減少させることができる方法であり、本発明
において最も好ましい方法である。なお、上記の方法に
おいて、二段処理の順を逆にすると、先に導入されたヘ
キサメチルジシラザンに基づくトリメチルシリル基の立
体障害のために、アルキルハロゲノシランは十分に反応
せず、目的とする高疎水性シリカを得ることができな
い。
In this method, an alkylhalogenosilane is reacted with an OH group on the silica surface to introduce in advance an alkylhalogenosilyl group having relatively small steric hindrance, and the remaining OH
This is a method in which a group is reacted with highly reactive hexamethyldisilazane. The introduction of an alkylhalogenosilyl group alone does not provide a product satisfying both the specific surface OH number and the modified hydrophobicity of the present invention, but further reacts highly reactive hexamethyldisilazane in the presence of steam. As a result, fine silica having extremely excellent hydrophobicity can be obtained. This method can increase the modified hydrophobicity and minimize the number of surface OH groups, and is the most preferable method in the present invention. In the above method, when the order of the two-step treatment is reversed, the alkylhalogenosilane does not react sufficiently due to the steric hindrance of the trimethylsilyl group based on hexamethyldisilazane introduced earlier, and the desired Highly hydrophobic silica cannot be obtained.

【0028】この方法において最初に行う微細シリカと
アルキルハロゲノシランとの接触の条件は、西ドイツ特
許第1163784号明細書に記載されている接触条件
を採用すれば良い。例えば、テトラクロロシランの火炎
熱分解法により製造された微細シリカを反応器中に投入
した後450℃程度に加熱し、微細シリカ1kg当りア
ルキルハロゲノシランを0.05〜1kgで、アルキル
ハロゲノシランと水蒸気との供給比率が水蒸気/アルキ
ルハロゲノシラン=1/3〜1/0.01(モル比)と
なるように、アルキルハロゲノシランと水蒸気とを反応
器中に窒素によって並流的に気送し、反応終了後は未反
応物や副生物を窒素でパージして乾燥する方法が好まし
い。
The conditions for the first contact between the fine silica and the alkylhalogenosilane in this method may be the contact conditions described in German Patent 1,163,784. For example, fine silica produced by a flame pyrolysis method of tetrachlorosilane is charged into a reactor and heated to about 450 ° C., and 0.05 to 1 kg of alkylhalogenosilane per 1 kg of fine silica is mixed with alkylhalogenosilane and steam. And an alkylhalogenosilane and water vapor are co-currently blown into the reactor with nitrogen so that the supply ratio of water and alkylhalogenosilane = 1/3 to 1 / 0.01 (molar ratio), After the completion of the reaction, a method is preferred in which unreacted substances and by-products are purged with nitrogen and dried.

【0029】このようにして、本発明の疎水性微細シリ
カを製造することができる。
Thus, the hydrophobic fine silica of the present invention can be produced.

【0030】[0030]

【発明の効果】本発明の疎水性微細シリカは、表面のO
H基の量が極めて少なく、しかも、ヘキサメチルジシラ
ザンとの接触によって疎水基が導入されており、極めて
疎水性の優れた微細シリカである。
The hydrophobic fine silica of the present invention has a surface
The amount of the H group is extremely small, and the hydrophobic group is introduced by contact with hexamethyldisilazane.

【0031】従って、本発明の疎水性微細シリカは、あ
る種の樹脂、たとえば、シリコーン樹脂に混合した場
合、濡れ性と分散性がよいために粘度の上昇が小さく、
また、粘度の経時安定性を向上させることができる。粘
度上昇が小さいことは、その樹脂に多量の微細シリカが
充填できる可能性がある。また、本発明の疎水性微細シ
リカを各種シーラントや樹脂に増粘剤として混合した場
合、粘度やチキソトロピー性の経時的な安定性を高める
ことができる。
Therefore, the hydrophobic fine silica of the present invention, when mixed with a certain resin, for example, a silicone resin, has a small increase in viscosity due to its good wettability and dispersibility.
Further, the stability over time of the viscosity can be improved. A small increase in viscosity may allow the resin to be filled with a large amount of fine silica. In addition, when the hydrophobic fine silica of the present invention is mixed with various sealants and resins as a thickener, the viscosity and the thixotropic property over time can be increased.

【0032】さらに、本発明の疎水性微細シリカは、上
記した用途の他にも、各種粉体、例えば、乾式コピー機
のトナー、粉状樹脂等、各種粉体の流動化剤としても好
適に用いることができ、かつ、湿度環境下で吸湿しにく
いため、その流動化性能や帯電量の環境変化が少なく、
好適に用いることができる。
Further, the hydrophobic fine silica of the present invention is suitably used as a fluidizing agent for various powders, such as toners for dry copiers and powdery resins, in addition to the above-mentioned uses. It can be used and hardly absorbs moisture in a humid environment.
It can be suitably used.

【0033】[0033]

【実施例】以下に実施例を掲げて本発明を詳細に説明す
るが、本発明はこれら実施例に限定されるものではな
い。なお、以下の実施例および比較例における各種の物
性の測定は以下の方法による。
EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In addition, the measurement of various physical properties in the following Examples and Comparative Examples is performed by the following methods.

【0034】1.表面OH基および平衡吸着水分量 カールフィシャー法により測定した。即ち、試料を1
20℃で12時間乾燥し(この操作により表面の吸着水
分はなくなりOH基のみとなる。)、また25℃相対湿
度80%の雰囲気中に試料を45日静置した(この操作
によって水分が吸着平衡に達する。)。各試料の測定は
京都電子工業社製カールフィッシャー水分計MKS−2
10型を用い、メタノールを溶媒とし直接シリカ表面の
それぞれの水分を定量した。滴定試薬には、HYDRA
NAL COMPOSITE 5Kを用いた。
1. It was measured by surface OH groups and equilibrium adsorbed water content Karl Tsu Shah method. That is, 1
At 20 ° C. and dried for 12 hours (this operation is only OH groups adsorbed moisture is no longer the surface by.), Also samples were allowed to stand 45 days in 25 ° C. and 80% relative humidity atmosphere (moisture by this operation is adsorbed Reach equilibrium). The measurement of each sample was performed using the Karl Fischer moisture meter MKS-2 manufactured by Kyoto Electronics Industry Co., Ltd.
Using model 10 with methanol as solvent
Each moisture was quantified. HYDRA as the titration reagent
NAL COMPOSITE 5K was used.

【0035】表面OH基数は、上記の方法で測定された
シリカ表面の水分から下記式により計算して求めた。
The surface OH groups were determined by calculating the water minutes following formula measured silica surface by the above method.

【0036】表面OH基数(個/nm2) = 668.9 × H2
O(wt%) /比表面積(m2/g) 2.炭素分析 シリカの表面疎水基が含有する炭素を1100℃、酸素
雰囲気中にてCO2に熱分解した後、微量炭素分析装置
(堀場社製EMIA−110型)によりシリカの含有す
る炭素量を分析した。
Number of surface OH groups (number / nm 2 ) = 668.9 × H 2
1. O (wt%) / specific surface area (m 2 / g) Carbon Analysis After pyrolysis of carbon contained in the surface hydrophobic group of silica into CO 2 at 1100 ° C. in an oxygen atmosphere, the amount of carbon contained in the silica is analyzed using a trace carbon analyzer (EMIA-110, manufactured by Horiba). did.

【0037】3.修飾疎水度 疎水性微細シリカは水には浮遊するが、メタノールには
完全に懸濁する。このことを利用し、以下の方法によっ
て測定した修飾疎水度をシリカ表面疎水基による疎水化
の指標とした。
3. Modified Hydrophobicity Hydrophobic fine silica floats in water but completely suspends in methanol. Taking advantage of this, the modified hydrophobicity measured by the following method was used as an index of hydrophobicity by the silica surface hydrophobic group.

【0038】疎水性微細シリカ0.2gを容量250m
lのビーカー中の50mlの水に添加した。メタノール
をビュレットからシリカの全量が懸濁するまで滴下し
た。この際ビーカー内の溶液をマグネチックスターラー
で常時攪拌した。疎水性微細シリカの全量が溶液中に懸
濁された時点を終点とし、終点におけるビーカーの液体
混合物中のメタノールの容量百分率を修飾疎水度とし
た。
0.2 g of hydrophobic fine silica is filled with a capacity of 250 m.
1 to 50 ml of water in a beaker. Methanol was added dropwise from the burette until all of the silica was suspended. At this time, the solution in the beaker was constantly stirred with a magnetic stirrer. The end point was when the total amount of hydrophobic fine silica was suspended in the solution, and the volume percentage of methanol in the liquid mixture of the beaker at the end point was defined as the modified hydrophobicity.

【0039】4.比表面積 柴田理化学社製比表面積測定装置(SA−1000)を
用いて、窒素吸着BET1点法により測定した。 5.pH測定 疎水性微細シリカ4gをはかり取り、先ずメタノール5
0mlを加え、次いで脱気された純水50mlを加えて
スターラーで10分間攪拌した後、液のpHを測定し
た。
4. Specific surface area The specific surface area was measured by a nitrogen adsorption BET one-point method using a specific surface area measuring device (SA-1000) manufactured by Shibata Rikagaku Co., Ltd. 5. pH measurement Weigh 4 g of hydrophobic fine silica, and first add methanol 5
0 ml was added, followed by 50 ml of degassed pure water, and the mixture was stirred with a stirrer for 10 minutes, and then the pH of the solution was measured.

【0040】6.残留NH3量 水−メタノール混合溶液によって疎水性微細シリカをス
ラリー化し、メトロオーム社製CH−9191型NH3
ガス電極により測定した。
6. Residual NH 3 amount Hydrophobic fine silica was slurried with a mixed solution of water and methanol, and CH-3191 type NH 3 manufactured by Metro Ohm Co. was used.
It was measured with a gas electrode.

【0041】7.粗粒 疎水性微細シリカ5gをはかり取り、先ずメタノール5
0mlに湿潤し、純水50mlを加え、超音波で5分間
分散した。分散後目開き45μm、開口面積12.6c
2の篩いを用い、流水を5L/分で5分間流通し、篩
上に残ったシリカを乾燥後定量した。
7. Coarse particles 5 g of hydrophobic fine silica is weighed, and methanol 5
The mixture was wetted to 0 ml, pure water (50 ml) was added, and the mixture was dispersed by ultrasonic waves for 5 minutes. 45 μm aperture after dispersion, opening area 12.6c
Using a sieve of m 2 , running water was circulated at 5 L / min for 5 minutes, and silica remaining on the sieve was dried and quantified.

【0042】8.シリコーンの粘度 ジメチルシリコーンオイル(粘度1000cs(センチ
ストークス))180gに疎水性微細シリカ9gを添加
し、常温においてディスパーを用いて3000rpmで
2分間分散させた後、25℃の恒温槽中に2時間放置し
た。試料をBL型回転粘度計を用い60rpmでの粘度
を測定した。
8. Silicone viscosity 9 g of hydrophobic fine silica was added to 180 g of dimethyl silicone oil (viscosity of 1000 cs (centistokes)), dispersed at 3000 rpm for 2 minutes at room temperature using a disperser, and then left in a thermostat at 25 ° C. for 2 hours. did. The viscosity of the sample was measured at 60 rpm using a BL-type rotational viscometer.

【0043】実施例1 テトラクロロシランの火炎熱分解で得られた製造直後の
比表面積300m2/gで表面OH基数が1.4個/n
2の親水性微細シリカ5Kgを内容積300Lのミキ
サー中において攪拌混合し、窒素雰囲気に置換を行っ
た。反応温度170℃において、ヘキサメチルジシラザ
ンを200g/分、水蒸気を22g/分で75分供給し
て疎水化処理を行った。反応後毎分40Lの窒素を30
分間供給し脱アンモニアを行った。結果を表1に示し
た。
Example 1 Tetrachlorosilane obtained by flame pyrolysis immediately after production had a specific surface area of 300 m 2 / g and a surface OH group number of 1.4 / n.
5 kg of hydrophilic fine silica of m 2 was stirred and mixed in a mixer having an internal volume of 300 L, and the atmosphere was replaced with a nitrogen atmosphere. At a reaction temperature of 170 ° C., hydrophobic treatment was performed by supplying hexamethyldisilazane at 200 g / min and steam at 22 g / min for 75 minutes. After the reaction, 30 L of nitrogen at 40 L / min.
For 10 minutes to remove ammonia. The results are shown in Table 1.

【0044】実施例2 テトラクロロシランの火炎熱分解で得られた製造直後の
比表面積280m2/gの微細シリカ5Kgを流動層反
応器に入れ、ジメチルジクロロシランを20g/分、水
蒸気を180g/分で450℃に加熱された流動層反応
器中に窒素によって並流的に40分間気送した。疎水化
処理後、未反応物や副生物は窒素でパージして乾燥し
た。以上の操作により比表面積235m2/g、炭素含
有量1.6wt%、表面OH基の0.45個/nm2
修飾疎水度52%の微細シリカが得られた。
Example 2 5 kg of fine silica having a specific surface area of 280 m 2 / g immediately after production obtained by flame pyrolysis of tetrachlorosilane was charged into a fluidized bed reactor, dimethyldichlorosilane was added at 20 g / min, and steam was added at 180 g / min. Was bubbled co-currently with nitrogen into a fluidized bed reactor heated to 450 ° C. for 40 minutes. After the hydrophobization treatment, unreacted substances and by-products were purged with nitrogen and dried. By the above operation, the specific surface area is 235 m 2 / g, the carbon content is 1.6 wt%, the number of surface OH groups is 0.45 / nm 2 ,
Fine silica having a modified hydrophobicity of 52% was obtained.

【0045】この微細シリカ5Kgを内容積300Lの
ミキサー中において攪拌混合し窒素雰囲気に置換を行っ
た。反応温度200℃において、ヘキサメチルジシラザ
ンを200g/分、水蒸気11g/分にて75分供給し
疎水化処理を行った。反応後毎分40Lで窒素を30分
間供給して脱アンモニアを行った。結果を表1に示し
た。
5 Kg of this fine silica was stirred and mixed in a mixer having an internal volume of 300 L, and replaced with a nitrogen atmosphere. At a reaction temperature of 200 ° C., hexamethyldisilazane was supplied at 200 g / min and steam at 11 g / min for 75 minutes to perform a hydrophobic treatment. After the reaction, nitrogen was supplied at 40 L / min for 30 minutes to remove ammonia. The results are shown in Table 1.

【0046】実施例3 実施例2において、ジメチルジクロロシランの供給量を
24g/分に増加したことにより、比表面積230m2
/g、炭素含有量2.2wt%、表面OH基数0.34
個/nm2、修飾疎水度56%の微細シリカが得られ
た。この微細シリカを用いたこと以外は実施例2と同様
の処理を行った。結果を表1に示した。
Example 3 In Example 2, the supply amount of dimethyldichlorosilane was increased to 24 g / min, so that the specific surface area was 230 m 2.
/ G, carbon content 2.2 wt%, number of surface OH groups 0.34
Particles / nm 2 , and fine silica having a modified hydrophobicity of 56% were obtained. The same processing as in Example 2 was performed except that this fine silica was used. The results are shown in Table 1.

【0047】実施例4 実施例2において、表面処理剤をモノメチルトリクロロ
シランに変更したこと以外は同様の処理を行った。この
操作により比表面積230m2/g、炭素含有量2.2
wt%、表面OH基数0.4個/nm2、修飾疎水度5
2%の微細シリカが得られた。この微細シリカを使用し
て実施例2と同様にヘキサメチルジシラザン処理を行っ
た。結果を表1に示した。
Example 4 The same treatment as in Example 2 was carried out except that the surface treating agent was changed to monomethyltrichlorosilane. By this operation, the specific surface area was 230 m 2 / g, and the carbon content was 2.2.
wt%, number of surface OH groups 0.4 / nm 2 , modified hydrophobicity 5
2% of fine silica was obtained. Using this fine silica, hexamethyldisilazane treatment was performed in the same manner as in Example 2. The results are shown in Table 1.

【0048】実施例5 実施例2において、ヘキサメチルジシラザンを200g
/分、水蒸気を11g/分で60分間供給して疎水化処
理を行った他は実施例2と同様に行った。結果を表1に
示した。
Example 5 In Example 2, 200 g of hexamethyldisilazane was used.
/ Min and water vapor was supplied at a rate of 11 g / min for 60 minutes to carry out the hydrophobic treatment. The results are shown in Table 1.

【0049】実施例6 実施例1において、比表面積380m2/g、表面OH
基数1.4個/nm2の微細シリカを出発原料に使用し
た他は実施例1と同様に行った。結果を表1に示した。
Example 6 In Example 1, the specific surface area was 380 m 2 / g and the surface OH
The procedure was performed in the same manner as in Example 1 except that fine silica having a group number of 1.4 / nm 2 was used as a starting material. The results are shown in Table 1.

【0050】比較例1〜2 実施例1および2において、ヘキサメチルジシラザンと
の接触時に水蒸気の添加を行わなかったこと以外は実施
例1および2と同様にして行い、その結果を表1に比較
例1および2として示した。
Comparative Examples 1 and 2 The same procedures as in Examples 1 and 2 were carried out except that no steam was added during the contact with hexamethyldisilazane. The results are shown as Comparative Examples 1 and 2.

【0051】比較例3 比表面積300m2/gの微細シリカに水分を吸着させ
た後に乾燥し、表面OH基数4個/nm2の微細シリカ
を得た。この微細シリカを用いて実施例1と同様にして
ヘキサメチルジシラザン処理を行い、その結果を表1に
示した。
Comparative Example 3 Water was adsorbed on fine silica having a specific surface area of 300 m 2 / g and dried to obtain fine silica having a surface OH group number of 4 / nm 2 . Using this fine silica, hexamethyldisilazane treatment was performed in the same manner as in Example 1, and the results are shown in Table 1.

【0052】比較例4 比表面積300m2/gで、表面OH基数1.4個/n
2の微細シリカ5Kgを内容積300Lのミキサー中
において攪拌混合し、窒素雰囲気に置換を行った。雰囲
気温度200℃にてジメチルシリコーンオイルを噴霧
し、引き続き電気炉で350℃に加熱し、微細シリカを
得た。その結果を表1に示した。
Comparative Example 4 With a specific surface area of 300 m 2 / g and a surface OH group number of 1.4 / n
5 kg of fine silica of m 2 was stirred and mixed in a mixer having an internal volume of 300 L, and the atmosphere was replaced with a nitrogen atmosphere. Dimethyl silicone oil was sprayed at an atmospheric temperature of 200 ° C. and subsequently heated to 350 ° C. in an electric furnace to obtain fine silica. The results are shown in Table 1.

【0053】[0053]

【表1】 [Table 1]

【0054】実施例7 実施例1〜6および比較例1〜2で得られた微細シリカ
を前記した方法にしたがってシリコーンと混合し、これ
を25℃の恒温槽中に保存し、保存の経過日数とシリコ
ーンの粘度との関係を図1に示した。
Example 7 The fine silica obtained in Examples 1 to 6 and Comparative Examples 1 and 2 was mixed with silicone according to the method described above, and this was stored in a thermostat at 25 ° C. FIG. 1 shows the relationship between the viscosity and the viscosity of the silicone.

【図面の簡単な説明】[Brief description of the drawings]

【図1】 図1は、微細シリカとシリコーンの混合物を
25℃の恒温槽中に保存したときの経過日数とシリコー
ンの粘度との関係を示すグラフである。
FIG. 1 is a graph showing the relationship between the number of days elapsed and the viscosity of silicone when a mixture of fine silica and silicone is stored in a thermostat at 25 ° C.

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭61−136909(JP,A) 特開 昭50−51494(JP,A) (58)調査した分野(Int.Cl.6,DB名) C01B 33/18 C09C 3/12 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-136909 (JP, A) JP-A-50-51494 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) C01B 33/18 C09C 3/12

Claims (3)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】単位表面積当たりの表面のOH基の数が
0.3個/nm2以下であり、且つ修飾疎水度が60%
以上であることを特徴とする疎水性微細シリカ。
1. The number of OH groups on the surface per unit surface area is 0.3 / nm 2 or less, and the modified hydrophobicity is 60%.
Hydrophobic fine silica characterized by the above.
【請求項2】単位表面積当たりの表面のOH基の数が
1.5個/nm2以下である微細シリカを水蒸気の存在
下にヘキサメチルジシラザンと接触させることを特徴と
する請求項1記載の疎水性微細シリカの製造方法。
2. The method according to claim 1, wherein the fine silica having the number of OH groups on the surface per unit surface area of 1.5 or less per nm 2 is brought into contact with hexamethyldisilazane in the presence of water vapor. Production method of hydrophobic fine silica.
【請求項3】単位表面積当たりの表面のOH基の数が
1.5個/nm2以下である微細シリカをアルキルハロ
ゲノシランと接触させた後、水蒸気の存在下にヘキサメ
チルジシラザンと接触させることを特徴とする請求項1
記載の疎水性微細シリカの製造方法。
3. The method according to claim 1, wherein the fine silica having the number of OH groups on the surface per unit surface area of not more than 1.5 / nm 2 is brought into contact with the alkylhalogenosilane and then brought into contact with hexamethyldisilazane in the presence of water vapor. 2. The method according to claim 1, wherein
A method for producing the hydrophobic fine silica according to the above.
JP15238293A 1993-06-23 1993-06-23 Hydrophobic fine silica and method for producing the same Expired - Lifetime JP2886037B2 (en)

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